Design and Demonstration of Creating Underground Gas Storage in a Fractured Oil Depleted Carbonate Reservoir

Abstract The supply-demand misbalances of natural gas in China require the creation of underground gas storages (UGS) available during peak winter demand and these UGS will probably play an important role in China natural gas market development. As far as know, among existing UGS in China, fractured oil depleted carbonate reservoir converted into UGS is unprecedented. In this paper, a simulation study using both 3D full-field black oil reservoir model and full-field multi-component reservoir model were undertaken to evaluate and demonstrate feasibility of creating UGS in a buried hill fractured oil depleted carbonate reservoir with bottom water, sufficient closure, a good quality and tight cap rock. History matching of the reservoir and single well pressure, water cut, liquid production rate was performed with the full-field black oil reservoir model. The full-field multi-component reservoir model was used to determine total gas storage capacity, working gas capacity, deliverability and injection capacity of the UGS. The simulation study characterized the UGS working mechanism, analyzed its sensitivity, optimized its design parameters, predicted field performance under various operating conditions and recommended the optimized developing UGS plan. Effects of the other three buried hills on the UGS are also incorporated into the two reservoir models. CNPC is further verifying our research efforts to decide duration of the UGS project.